The meme started as eating paste, back when that meant wheatpaste (made from flour and water). In that context it's less surprising that kids might try to eat it!

I wonder if there's been a bit of a conflation with the other meme, about sniffing glue, which has also lost much of its context considering that rubber cement and other similar types of glue which contain volatile solvents are also less widely used than they once were.